Conventional knitting units of circular knitting machines are traditionally associated with more than 100 yarn supply bobbins. When certain yarns are employed for forming the knitted fabric, dust, lint and waste fibers (collectively referred to hereinafter as "fiber waste") are generated by engagement of the yarns with the machine's yarn feeding, guiding and/or other components of the knitting machine and creel. The amount of fiber waste set adrift in the ambient air is substantial. This amount of fiber waste tends to increase as the operating speed of the knitting machine increases. Once the fiber waste has become airborne, it tends to settle upon the yarn feeders, yarn guides and the knitting unit of the knitting machine, and even upon adjoining machines.
This fiber waste occasionally gets knitted into the fabric causing defects in the fabric and in some cases, damage to the needles and other components of the knitting unit. This accumulation of fiber waste necessitates frequent overalls of the knitting units on the machine which is both costly and time consuming.
Various kinds of devices have heretofore been proposed for removing fiber waste generated by the knitting unit. The majority of the prior devices employ either a motor driven fan or an air blower to blow the fiber waste away. It has also been proposed to provide a cover about each knitting machine, and to install an exhaust duct near the machine so that the machine operator may gather the fiber waste and introduce it into an exhaust duct. The large installation costs associated with such a method make it less desirable. In addition, this method requires shielding the machine body which negatively affects access to the machine and the surrounding work environment. Moreover, once lubricants, such as oil, etc., stick on the shielding member, fibers tend to adhere to the shielding member which is both unsightly and unsanitary.
As disclosed in U.S. Pat. No. 5,177,985, the assignee of the present invention has previously developed a system for the collection and removal of fiber waste which utilizes a fixed suction cylinder which cooperates with the suction/blowing means to direct fiber waste laden air from the knitting unit into a filter means. While this system constitutes a marked improvement in fiber waste removal and collection from circular knitting machines, the system does have limitations due to the fixed character of the suction cylinder.
As the operational speed of the knitting machines increases, the elements of the knitting unit begin to overheat, causing heat expansion which results in distortion of the cylinder and its surrounding components. This distortion in turn causes degradation in the accuracy of the knitting machine. However, such distorting and degradation could be prevented if the knitting machine was cooled during operation. Heretofore, no effective cooling of the knitting unit during operation has been made available.